There are a number of wrenches currently available that can be used to tighten or loosen a nut or headed bolt. One type of flat wrench is of a fixed size and shaped to fit a single nut or bolt, while a wrench with adjustable jaws can be used for nuts or bolts of varying sizes. Socket wrenches are also made to fit a specific nut or bolt. All of these wrenches require a turning arc that is determined by the shape of the nut or bolt. When the socket or jaws of the wrench is shaped like the nut or bolt head, a specific turning arc is needed for the wrench to be effective. For example, a square nut or bolt requires a minimum turning arc of 90° while a hexagonal nut or bolt requires a minimum turning arc of 60°. This means that the wrench must be turned at least by the minimum arc before it can be removed from the nut and reseated. In many instances the location of the nut or bolt does not provide enough space to permit the use of such wrenches. Wrenches with ratchet mechanisms are also well known, but are subject to breakage under excessive forces and can usually be rotated in only one direction.
Doughty, in U.S. Pat. No. 1,355,455, teaches a ratcheted socket wrench specifically designed for use in automobiles where there is limited access to certain nuts and bolts. This wrench has two rotatable ratchet wheels, each on an opposite side of a shank. The two wheels are rotatable with the socket member and wrench head. There is a pawl associated with each ratchet wheel and a pawl releasing member for each side. When the wrench is rotated in one direction one wheel is engaged and the pawl on the other side is released. When rotated in the opposite direction the other wheel is engaged and the first pawl is released. This wrench can be use to both tighten and loosen a nut or bolt and uses a small turning arc, but the mechanism can be subject to breakage under pressure. Summers teaches a wrench designed for use on Ford automobiles in areas with very limited access. (U.S. Pat. No. 1,434,635) The bolt engaging part of the wrench is a spring loaded ratchet mechanism controlling the rotation of a socket. The wrench has a handle consisting of a long solid rod with an L-shaped configuration. The end is bent over upon itself to provide a hand grip. Additionally, the wrench head can be rotated 180° and held fast by a set screw. The combination of handle shape and two head positions enables access to tight areas. Another socket wrench designed for use in motor vehicles has a long thin flat handle with an L-shaped end portion for use as a grip and to provide leverage. The long handle provides access to tight areas. This patent teaches the use of a hexagonal socket interior and also suggests the use of a square, octagonal or fluted socket interior. (Curtis, U.S. Pat. No. 2,601,800)
A wrench consisting of two pieces is taught by Faw in U.S. Pat. No. 1,504,035. A simple socket has an elongated barrel with an axial hexagonal passage and a transverse round passage. A straight handlebar of hexagonal cross section fits the axial passage tightly and the transverse passage loosely. To seat the nut the handlebar is placed in the axial passage and is rotated between the palms of the hands until the nut is screwed as tightly as possible. The handlebar is then inserted into the transverse passage providing considerable leverage to complete the tightening of the nut. In the axial position the wrench can be used in a limited space, but when it is necessary to make the nut tight, a much larger turning area is required since the transverse use requires the full area traversed by the handlebar.
A novel bolt or nut head is taught by Newell et al. in U.S. Pat. No. 3,482,481. The head is frustoconical with two sets of grooves. The grooves in each set are parallel and oblique to the generatrix of the cone. One set of grooves slants to the right and the other to the left. The cooperating wrench has two ends, each with a frustoconical socket having one set of ribs, the set at one end corresponding to the right slanting grooves and the set at the other end corresponding to the left slanted grooves. One end of the wrench is used to tighten the bolt and the other to loosen it. The frustoconical shape requires the wrench to be separated only a small distance from the bolt head but the turning arc is determined by the spacing of the ribs. The wrench and bolt head must be used as a combination and neither can accommodate or be accommodated by conventional hardware.
British patent No. 16,793 to Delacroix describes a rod having one end with five surfaces, each with a raised cross. The rod is used with a set of sockets to fit different sized nuts. Each socket has two notches in its upper surface. The notches cooperate with the crosses. Each cross connects the rod to the socket at a different angle which enables access to a different limited space. German patent No. 575,904 to Forst shows a socket wrench consisting of a shank with connecting means at both ends and a socket member with two sockets of different interior diameters set at right angles to each other. Each socket interior cooperates with one end of the shank. The socket not attached to the shank forms the usable part of the wrench. This wrench can only be used with nuts and bolts of sizes corresponding to the socket selected.
Patent 604,812 from Great Britain describes a one piece socket wrench with a fluted socket interior specifically designed for use when the nut is so close to a wall that the socket cannot fit over the nut. A part of the exterior wall of the socket is ground off to form a sloping face. The socket is placed over the nut with the ground face adjacent to the wall or other obstruction. The nut is turned as far as possible and the socket is removed and reseated.
The ratchet wrenches described above are subject to breakage under large forces while many of the other wrenches are made for specific uses and are not practical for general usage. There is a need for a wrench that can be used to tighten or loosen a nut or bolt situated in any hard to reach area and where only a small turning arc is available. There is a need for a wrench that has minimal components and can withstand the large forces often necessary to remove a nut or bolt that has been in place for a long time. There is a need for a wrench that is adaptable for nuts and bolts of different sizes and shapes and one that is inexpensive and simple to manufacture.